The long-term aim of the project is an understanding of the causes for the hearing disability experienced by cochlear-impaired listeners in background noise. Of particular interest in the present project are across-frequency processes involving time-varying sounds in normal-hearing and hearing-impaired listeners. One specific aim of this project is to determine the stimulus characteristics that are associated with poor temporal analysis in cochlear-impaired listeners, both for within-channel and for across-channel auditory processes. A related goal of the studies in this area will be to determine the role of loudness recruitment in temporal analysis. The second specific aim of the project is an understanding of comodulation masking release (CMR) in terms of competing detection cues. A particular focus here is the influence of competing cues in cochlear-impaired listeners where some cues may be coded well and others coded poorly. The third specific aim is to determine how temporal information is combined across frequency in temporal analysis. One goal here will be to determine how across-frequency energy is combined in a hearing-impaired ear, when some information is associated with regions of good hearing and other information is associated with regions of poor hearing. A second goal is to determine how temporal information is combined acrosS frequency in normal hearing, testing hypotheses that the ear can sum energy acrosS frequency, or that the ear can choose the auditory channel containing the "best" information. The fourth specific aim determine the effects of cochlear hearing loss on the recognition and discrimination of signals in comodulated noise backgrounds and in backgrounds where binaural difference cues are present. The studies in this area should provide new information about the effect of cochlear loss on signal recognition/discrimination in monaural and binaural masking release. Testing will be performed in a sound-treated room, using forced choice adaptive procedures. Subjects will include normal-hearing control groups and groups of listeners having hearing loss of cochlear origin. Data will be analyzed using simple descriptive statistics, correlation, and analysis of variance.